Let's draw a triangle.

And let's add perpendiculars from B and C to the respective opposite sides.

Can a similar triangle be made?

Or can you make a similar triangle to ƒ¢ABC based on this figure?

If you use DGS to find the answer of this question, you can observe various cases by moving figure.

It is difficult to think the proof, but you may find an interesting result. How about this?